The present invention relates to a system for diagnosing anomalies or breakdowns in a plurality of types of electronic control systems installed in motor vehicles with internal combustion engines, each type of control system including a respective plurality of sensors for sensing the operating conditions of the engine and electrically-controlled actuator means connected to an electronic control and operating unit, which is usually different for each type of control system, the unit having at least one output and being programmed to carry out the auto-diagnosis of anomalies or breakdowns in the control system and to provide at the output serial electrical auto-diagnosis signals containing information on the operating conditions of the control system.
In modern motor vehicles there are ever more applications of complex electronic control systems for controlling various pieces of apparatus and functions, such as, for example, the ignition, the fuel injection, brake control, air conditioning, etc. According to the function or apparatus controlled, these systems have different characteristics. In general, however, their structure includes an electronic control unit (controller), a plurality of sensors, and a plurality of actuators and related wiring for their connection to the control unit.
The adoption of electronic control systems has enabled the performance and comfort offered by motor vehicles to be improved substantially. The application of such systems, or at least many of them, is ever more widespread, not only in more expensive and prestigious cars but also in average and cheaper cars.
The adoption of electronic control systems in vehicles has created problems in the diagnosis, that is, recognition, of breakdowns and anomalies in operation, in order to enable rapid replacement or repair of the defective or broken components. These problems arise both during operational testing of motor vehicles by the manufacturers and in after-sales service centres.
These problems are complicated and not easy to solve in view of the fact that the electronic control systems used in the various motor vehicle models produced differ even in those from the same manufacturer. Moreover, service centres are traditionally more prepared to face and solve problems of a mechanical nature than electronic problems.
In any case, in order to identify defects or breakdowns in electronic systems with a certain degree of rapidity, a very profound knowledge of such systems is needed by the personnel carrying out the diagnosis.
In order to facilitate diagnosis of such problems, specific pieces of apparatus have been developed, each of which is dedicated exclusively to the identification (diagnosis) of the defects or breakdowns in a particular electronics system. Such apparatus is generally very expensive and also requires adequate preparation on the part of the personnel to enable them to use it correctly.
In the current situation, after-sales service centres must have highly specialised personnel with a deep knowledge of all electronic systems installed in vehicles they expect to service. Moreover, it is also necessary for these centres to have all the specific test apparatus available for diagnosing breakdowns of these systems.
The problem is thus felt particularly with regard to so-called "intermittent faults", that is, those failures which occur only under particular conditions of use of the vehicle and which cease to manifest themselves when the latter is stationary in a service centre.